Iâd like to test my understanding of âbad ticksâ â¦ See the longest candles in yesterdayâs 30-second chart for SPY (all times are EST) attached. This data was not recorded in real time, but downloaded today from eSignal. Some of these longest candles occurred during Regular Trading Hours (09h30 â 16h00 EST), some before, some after. Q1 - What are these very long candles (âbad ticksâ)? I understand them to be trades (probably large trades, âblock tradesâ?) made âoff the exchange floorâ (negotiated directly between âblock dealersâ and their clients?) and reported to the exchange some material time after the fact. Is this correct? Q2 ââBad ticksâ of the type referred to above occur in equity markets, but not in futures markets (as âblock tradesâ of the type described above are a feature of equity rather than futures markets?). Correct? Q3 - What rules might one use to "clean" "bad ticks"?